FAT12 and FAT16 description. ------------------------- HIW Document Server Index Updated 09 Nov 96 ------------------------- Contents: ATA news - 2 ATA FAQ - 8 CHS Translation part 1 of 2 – 27 CHS Translation part 1 of 2 – 38 DOS Floppy Disk Boot Sector - 46 Facts and Fiction Volume 1 – 56 Master Boot Record - 73 OS2 Boot Sector – 79 Partition Tables part 1 of 2 – 89 Partition Tables part 2 of 2 – 96 The What's New Bulletin - 101 Help document - 104 -------- ATA NEWS -------- November 1996 by Hale Landis <[email protected]> Well... It is about time I got around to updating the document! Much has happened during 1996 in the ATA/ATAPI world. Mostly the level of chaos has increased but a few good things did happen. ----- X3T13 ----- One of the good things that happened was in Jan 1996 -- the X3T13 committee was formed. X3T13 is responsible for all of the ATA standards (ATA-1,...ATA/ATAPI-4, etc). Finally the ATA committee work is free of the X3 SCSI committtees (X3T10, etc) and can proceed at its own pace. The ATA/ATAPI Working Group of X3T13 meets once a month and during 1996 the meetings have been attended by many people and much good progress has been made towards producing an ATA/ATAPI-4 document (see below). X3T13 is one of many Technical Committees in the Accredited Standards Committee (ASC) X3. This committee is authorized to create and maintain certain computer industry standards within the USA. Many of these standards are submitted to the International Standards Organization (ISO) to become worldwide standards. X3T13 is currently responsible for all of the ATA standards. A different committee, X3T10, is responsible for the SCSI standards. X3T13 (and X3T10) replaced an older committee know as X3T9 which did the early ATA and SCSI standards. ----------------- THE ATA STANDARDS ----------------- The ATA standard (the real IDE/EIDE standard) comes in several flavors: ATA (also called ATA-1), ATA-2, ATA-3 and now ATA/ATAPI-4. Note that while an X3 committee is working on such a document, you can usually get the document via the Internet. However, once it becomes an official ANSI standard the ONLY way to get a copy is on paper and such copies generally cost $50 each. (This is really stupid and I think you should tell ANSI and X3 that. I'll tell you how to do that in a future version of this document). ----------- ATA (ATA-1) ----------- ATA (ATA-1) is ANSI document number X3.221-1994. ATA is the real standard for what is widely known as IDE. ----- ATA-2 ----- ATA-2 is the real standard for what is widely known as EIDE. The ATA-2 document has been delayed about two years while many editorial changes where made. There have been no technical changes made to the document. ATA-2 is expected to be published as an ANSI standard in Dec 96 or Jan 97. ATA-2 is ANSI document number X3.279-1996. ATA-2 introduced higher speed data transfer modes, PIO Modes 3 and 4 plus Multword DMA Mode 1 and 2). These modes allow the ATA interface to run data transfers up to about 16MB/second. ----- ATA-3 ----- ATA-3 introduces some new features of questionable value: SMART and Security. (more about these below). Note that ATA-3 does NOT introduce any new (faster) PIO or DMA data transfer modes (there is no such thing as PIO mode 5!). ATA-3 has completed its public review and should be approved in early 1997. When published lated in 1997 as an ANSI standard it will be know as X3.298-1996 (or perhaps X3.298-1997). ----------- ATA/ATAPI-4 ----------- The charter of X3T13 is to watch over the previously published ATA standards (ATA-1, ATA-2 and ATA-3) and to produce the next ATA standard. The next standard will merge the ATA interface, used mostly by hard disk drives, with the relatively new ATAPI interface used by all the new CD-ROM drives and tape backup devices. The original ATA-4 document has been renamed to ATA/ATAPI-4. ATA/ATAPI-4 adds and changes many things. Here is a brief list: - Many old ATA commands and features are now obsolete, such as the Format Track and Read/Write Long commands. - There is a new data transfer protocol named Ultra DMA that adds data integity (via a CRC check) and much higher data transfer rates (up to 33MB/second). - The ATAPI command and reset protocols are new. - There is a command overlapping and command queuing protocol for ATAPI devices and most likely this will be extended to include ATA devices. See below. - There are many new minor features for both ATA and ATAPI devices. ----- ATAPI ----- So just what is ATAPI anyway? ATAPI is the real name of the new CD-ROM (EIDE CD-ROM) and tape (ATAPI tape or EIDE tape) interface. This interface was originally developed by a group of CD-ROM companies with lots of help from Western Digial. ATAPI did not start as an ANSI standard -- it was a specification published by the Small Form Factor (SFF) committee. SFF is an ad hoc disk drive industry committtee that usually concerns itself with things like connectors, the location of mounting holes and other physical configuration stuff. The original SFF document for ATAPI was called SFF-8020. ATAPI introduced a new command execution protocol for use on the ATA interface so that these new CD-ROM and tape drives could, in theory, be on the same ATA cable with an ATA hard disk drive. Basically, the ATAPI Packet command, command code A0H, is used to send what looks like a SCSI CDB accross the ATA interface. The actual data transfer (from/to the device's media) is done using the ATA PIO or DMA protocols. If you want to know what "SCSI like" commands are accepted by ATAPI devices then you should probably read the appropriate SCSI-3 document(s) for back ground information. Then get the appropriate SFF document for the ATAPI device type, for example, SFF-8020 describes the ATAPI CD-ROM "SCSI like" command set. There are many of these ATAPI "command set" documents floating around the industry today and even keeping a list of them is difficult. Some others I know of are: QIC-157 (ATAPI tape), SFF-8070 (ATAPI Removable Rewritable Media), SFF-8080 (ATAPI CD-R/E) and SFF-8090 (Commands for DVD). Locating some of these documents can be difficult. ------------------- ATA-3 SMART FEATURE ------------------- Every so often the ATA hard disk drive marketing folks think they need a new "feature" to sell. Self Monitoring And Reporting Technology is just that -- a bunch of marketing junk. This feature allows a drive to monitor itself and report to the host system when it thinks it will fail. (Don't laugh!) This ignores the fact that the vast majority of all drive failures are sudden and without warning, usually on Monday morning when the system is turned on after being off all weekend. ---------------------- ATA-3 SECURITY FEATURE ---------------------- The Security feature is another marketing idea. Without understanding the true meaning of data security and what it really takes to secure data, this feature was added in ATA-3. Apparently some ATA marketing people think this will prevent "bad guys" from stealing notebook computers in airports! The feature allows a drive to have two 32-byte "passwords" and allows the drive to be "locked" until the one of the passwords is presented to the drive. When locked the drive does not allow reads or writes to the media. One of the many problems with this feature is that a drive with no passwords active can be given a "random" password that no one knows. This can make the drive useless. ----------------------------------- ATA/ATAPI-4 COMMAND OVERLAP/QUEUING ----------------------------------- ATAPI devices are mostly very slow devices. One of the things that the early computer designers learned in the 1950's was that you don't put slow devices on the same interface with fast devices. But this lesson was lost and the ATAPI folks are trying to convince you that it is no problem to mix ATA and ATAPI devices on the same interface. But, of course there is. And now to "solve" this performance problem, the ATAPI people have invented "command overlap" so that a command to an ATA hard disk can be executed while a command to a slow ATAPI device is in progress. Now a few people think this should be extended to include "command queuing". So far the ATA/ATAPI-4 document describes only a very limited method to do these things and only on an ATAPI device. But there are now some ATA folks saying that ATA devices should be able to do the same things. The bottom line: If you really want poor performance and hangs and other strange things happening to your computer, then you definitely want these features! But like SMART and Security, we will probably get this junk in both ATA and ATAPI soon. To date I know of no devices that actually implement this and I don't know of any host software that tries to use it. ----------------------------- THE FUTURE (OR WHAT IS 1394?) ----------------------------- What do you get when a bunch of software people at Microsoft try to design hardware? You get a document named "PC 97". PC 97 is an attempt by Microsoft to tell the system builders and hardware designers how to design hardware so that it will be supported by Microsoft's operating systems starting in 1997. If this all sounds a little strange to you, just wait until you real the PC 97 documents! PC 97 is attempting to replace all existing motherboard sockets and device interfaces with two new serial bus interfaces.